The linings of the oral/nasal cavity contain dendritic cells (DCs) within the epithelia and underlying lymphoid tissues (plasmacytoid and myeloid DCs, PDCs and MDCs) that orchestrate innate and adaptive immune responses to pathogens or vaccines breaching the mucosa. Producing and responding to innate factors, DCs can contribute immediately, while activated DCs (elevated IL-12, IL-15, costimulatory molecules) stimulate strong adaptive T and B cell responses, together affording protective immunity. DC activation mediated by TNF-TNFR and TLR family members is critical for vaccine efficacy. Capitalizing on this, we are exploring CpG-C immunostimulatory oligodeoxynucleotides (ISS-ODNs) that potently activate PDCs as well as B cells to augment immune responses and improve oral/nasal vaccine effectiveness. We propose that CpG-C ISS-ODNs will induce PDCs to secrete type I IFNs to favor MDC and B cell activation and also directly trigger B cells in the tonsils. This activated tonsillar milieu will drive innate and Th1 type adaptive responses needed to control virus infection (systemically and mucosally). Combined with this we are including the chemically inactivated virus vaccine, AT-2 virus, that provides a wealth of antigenic determinants to elicit broad-acting immunity. Specifically, we will employ a mutated form of SIV in which the V1 and V2 regions of envelope have been deleted, (V1V2. This deletion results in the virus being more sensitive to Ab neutralization suggesting that the resulting open conformation of envelope exposes the "neutralization-sensitive epitope" and that the AT-2 form of (V1V2 might induce particularly effective B cell responses in addition to solid T cell responses. This proposal will use the SIV-macaque system to demonstrate that CpG-C ISS-ODNs can be used to effectively activate DCs and B cells of the oral mucosal associated lymphoid tissues to amplify immunity against an orally administered AT-2 SIV vaccine. Within this, we will explore: (i) how these cells respond to native vs (V1V2 SIV in the presence of CpG-C ISS-ODNs and (ii) if CpG-C ISS-ODNs and AT-2 deltaV1V2 applied to the tonsils stimulate potent SIV-specific T and B cell responses in naive and healthy, infected macaques. This proof-of-principle approach will allow us to formally show the feasibility of CpG-C ISS-ODN-activation of mucosal APCs to improve oral/nasopharyngeal vaccination to protect against HIV as well as bolstering existing immunity to eradicate infection. This will provide the basis for future studies in which we plan to extensively explore application of this strategy for vaccine vs therapeutic approaches against HIV.